Waste Fragmentation via Superheated Steam Decompression
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Solution Overview
Problem
Existing methods for waste fragmentation, such as those described in US Patent 4,540,467 and EP-A-1 628 736, are inefficient in fragmenting plastics and require additional chemical treatments, leading to suboptimal results and increased costs, while also failing to effectively reduce the volume of bulky waste items like plastics bottles for recycling or disposal.
Innovation Solution
A method involving repeated cycles of subjecting waste items to superheated steam and rapid decompression in a pressure vessel, eliminating the need for chemical pre-treatments and achieving more effective fragmentation, including plastics, by using superheated steam at pressures above atmospheric pressure followed by flash decompression, which can convert plastics into a powder form suitable for recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical pre-treatments are used for waste fragmentation, then the fragmentation of certain materials may be improved, but the process complexity and cost increase
Solution Approach 1:
The patent removes chemical pre-treatment steps from the waste fragmentation process, extracting only the essential mechanical and thermal actions (pressurization and rapid decompression) needed to achieve effective fragmentation of diverse materials including plastics, without the complexity of chemical handling and selection
Solution Approach 2:
The pressurization-decompression system serves multiple functions: it fragments plastics, delaminates laminated articles, and processes various waste types without requiring different chemical treatments for each material type, making the process universally applicable
2Ease of operation
If single-stage pressurization and decompression is used, then the process simplicity is maintained, but the fragmentation effectiveness is insufficient
Solution Approach 1:
The patent employs repeated cycles of pressurization and rapid decompression, where each cycle progressively fragments the waste material. This periodic action maintains operational simplicity while achieving cumulative fragmentation effectiveness that single-stage processes cannot attain
Solution Approach 2:
Each pressurization cycle prepares the material for the subsequent decompression cycle, with the pressurization phase embedding energy and moisture into the material that is then released during decompression to enhance fragmentation in the next cycle
3Productivity
If rapid decompression is used to fragment waste, then the fragmentation speed increases, but the control over fragmentation degree becomes difficult
Solution Approach 1:
The patent dynamically adjusts process parameters including pressure levels, decompression rates, and cycle durations to control the degree of fragmentation. This dynamic control allows rapid fragmentation while maintaining precision over the final product specifications
Solution Approach 2:
The process incorporates monitoring and adjustment mechanisms that provide feedback on fragmentation progress, allowing control over the final fragmentation degree while maintaining high processing speeds through optimized cycle parameters
4Ease of operation
If bulky waste items are disposed of without fragmentation, then the disposal process is simple, but the transport and landfill efficiency are reduced
Solution Approach 1:
The patent segments bulky waste items into smaller fragments through repeated pressurization-decompression cycles, reducing overall volume while maintaining disposal simplicity. This segmentation enables more efficient transport and landfill utilization without complicating the disposal process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves significant volume reduction and controlled fragmentation of waste items, including plastics, without chemical pre-treatments, effectively addressing the limitations of previous technologies by producing a fragmented form that is more amenable for recycling or disposal, with the added benefit of maintaining high-quality fiber recovery from laminated articles.
Implementation Method 1
subjecting said item or items to an atmosphere of superheated steam in the vessel of at least 0.5 bar above atmospheric pressure
Implementation Method 2
decompressing the vessel to achieve a pressure reduction of at least 0.5 bar in at most 5 seconds
Implementation Method 3
The rapid reduction in pressure is stated, in US 4 540 467, to allow a sudden explosive decompression of the contents of the vessel which results in a rapid expulsion thereof from the vessel. During the decompression and expulsion, moisture and a certain proportion of other liquid contained in the waste material flashes to steam and vapour.
Implementation Method 4
The steam serves to heat and pressurise the contents of the vessel to a desired temperature and pressure
Data Source
AI summary
A method of fragmenting a discrete waste product item or a combination of discrete waste product items, the method comprises the steps of: (e) introducing said discrete waste product item or combination of discrete waste product items into a pressure vessel, (f) subjecting said item or items to an atmosphere of superheated steam in the vessel of at least 0.5 bar above atmospheric pressure, (g) subsequently decompressing the vessel to achieve a pressure reduction of at least 0.5 bar in at most 5 seconds, and (h) repeating steps (b) and (c) to effect fragmentation of said waste product item or combination of waste product items.